The processor

The processor is the main component of a computer that performs information processing. Modern processor consists of the following main units:

The processor is the main component of a computer that performs information processing

  1. control unit;
  2. registers instructions and data;
  3. arithmetic logic unit (ALU);
  4. unit operations with real numbers (FPU);
  5. buffer memory (cache) of the first level, separate for instruction and data;
  6. buffer memory (cache) of the second level;
  7. the system bus interface;

In simplified form, the processor operates as follows. The control unit loads instructions and data from RAM by placing them in a buffer memory of the second level, where the data is coming in your first-level cache, and instructions - to their first-level cache. From the first level cache commands and data are placed into registers. An arithmetic logic unit (ALU) takes from registers instructions and data, executes predetermined operations and stores the result back into the registers. If the operation is finished, the result is moved first in the first level cache, then - in a second level cache, and finally written into the RAM. This sequence forms a CPU operating current.

The processor is characterized by a clock speed, measured in megahertz or gigahertz and is characterized by the speed of elementary operations. The higher the CPU clock frequency, the higher the performance, and, of course, price.

Processor performance depends not only the clock frequency but also the maximum number of instructions executed per cycle (IPC). In today's competitive architectures are two fundamentally different approaches: one based on increasing the operating frequency (Intel), and the second - on the performance of the processor maximum number of instructions per cycle (AMD).

An important feature of the processor is a bit width processed data, which can be internal and external. Internal bit width - the number of bits that the CPU can process per clock cycle. External bit width is determined by the bit width of the system bus. Processor bit width is characterized by internal rather than external bit width. A bit depth determines the maximum amount of addressable memory.

The processor has its own memory, called registers. When processing data, intermediate results the processor records in the internal registers that work, in fact, at a clock frequency of the processor.

The speed of modern memory an order of magnitude inferior to the processor speed. If he gets the data directly from the memory, it would be idle most of the time. Therefore, the processor has a buffer memory (cache). The cache is divided into two parts (two levels):

  • the first level (Level 1, L1) - smaller in size (usually 8-128 KB);
  • the second level (Level 2, L2) - greater in volume (up to 4 MB);

The processor consists from the following components: an arithmetic logic unit (ALU), performs the processing of integers and a data processing unit with a floating point (FPU), performs operations on floating point data - are two types of data which are processed by the processor in various ways.